Asynchronous Motor Command Filtering Discrete Control Based On Neural Network

Induction Motor(IM)plays an important role in the power systems of industry and transportation because of the advantages of simple design,high reliability and simple price.At the same time,the IM drive system has the high orders,strong coupling and parameter uncertain nonlinear drive system model.It is very easy to receive the disturbances of parameter change and external load disturbance,which makes the drive system has lower dynamic and static performance and worse control accuracy.On the other hand,microprocessors were quickly employed in discrete control fields with the advantages of low production cost,long service life,fast operation and so on.Discrete control is superior to continuous control in stability and realizability,and can describe real engineering system more accurately,thus,it has great practical significance to research IM discrete control.However,there are many input saturation nonlinear constraints in the actual engineering system,which will affect the stability of the system,reduce the control performance,and increase the computational complexity of the control algorithm.Therefore,this problem should be taken into account when designing control algorithms.In summary,this paper combines command filtering control and adaptive neural network technology to construct the IM discrete controller under the condition of input saturation nonlinear constraints.The main research results of the thesis are listed as follows1.The IM discrete system model can be obtained from the continuous model by using Euler formula.2.Based on the discrete-time model of IM system,the principle of command filtering neural network approximation is applied in this paper.A scientific and effective discrete control algorithm is constructed for IM speed regulation control and position tracking control.The neural network technology is used to approximate the unknown nonlinear functions in the discrete system.The neural network adaptive method can solve the adverse effects of higher order functions in discrete system.For the problems of "explosion of complexity" and "noncausal problem" existed in the traditional backstepping method,the paper introduces command filtering control,which can solve the above two problems smoothly.3.In this paper,the input saturation nonlinear constraints are considered for the first time in discrete IM system,which is beneficial to the application of the control algorithm in practical engineering system.4.Lyapunov stability analysis is used to prove the stability of IM discrete dynamic system.The simulation results show that the discrete control algorithm in this paper can ensure all the signals in the closed-loop system are bounded and the input voltages are always kept between the limits of saturated inputs.The controllers designed in this paper have better control effect on IM discrete system and stronger ability to suppress sudden change of load torque,which shows the strong robustness and superiority of this method.